Technical Abstract:
Ribotyping using the automated RiboPrinter system (DuPont Qualicon, Wilmington, DE, USA) has been described previously as an effective means for interlaboratory comparisons of molecular profiles from the common foodborne pathogens, C. jejuni and C. coli. The restriction enzyme PstI is typically used, generating molecular profiles of 4-6 bands over a size e range of 5-50 kb. We compared PstI-generated ribotypes from poultry isolates obtained as part of the National Antimicrobial Resistance Monitoring System from across the USA (n~75), and those from a cross- sectional survey of poultry isolates across N. Ireland (n~180). Numerical analysis (BioNumerics; Applied Maths, Kortrijk, Belgium) of the individual data sets identified major differences between the two population structures. The USA sample set was extremely diverse. Other than one group of 6, and one of 7 identical profiles, no groups containing >2 isolates were identified. In contrast, approximately 2/3 of the N. Ireland sample set comprised 8 major groups, each containing 8- 40 isolates. These differences in population structure may reflect the different geographical backgrounds from which the strains were isolated; N. Ireland is very small and relatively isolated compared to the wide, unrestricted expanse of the USA.